Leno actually told Keith Olberman, "10:30 is like 11:30 used to be" (see clip above). And he told the Times, "More people — and younger people — are going to bed at 11 o’clock because they carpool or they have to get up at 6."
This was silly to begin with, because anyone who actually buys his own gas knows that the price is plummeting, so those carpools are going to die off, and people can resume staying up late and waking up the next morning at the last possible minute, before getting stuck in traffic.
But even when gas prices were high, people weren't turning in any earlier, according to Nielsen stats crunched by the website TV By the Numbers :
According to Nielsen data, 6% fewer 18-49 year olds are watching TV between 10pm-11pm [Leno's future timeslot] than were watching 5 years ago. 4% fewer 18-34 year olds are watching between 10pm-11pm than five years ago. If you want a broader view, looking at 25-54 year olds, viewing between 10pm-11pm is down 7% over the last five years.
Meanwhile, the trend is UP for viewing between 11:30pm-12:30am over the last five years among 18-49 year olds (1% increase) and 18-34 year olds (5% increase) and is completely flat among the broader 25-54 demographic.
Leno could have easily checked Nielsen stats himself. But making up a fake trend probably sounded better than admitting that he picked NBC because it offered him more money, or because if he fails he can always blame the new timeslot. If he had lost against Letterman or O'Brien at ABC at 11:30, suddenly people would be saying he was only on top for so long due to his lead-in, or help from NBC producers.
Either that or the perennial interview query "Can something like the Tonight Show succeed at 10 p.m." Is such a silly question that Leno decided it deserved a sillky answer.